Which typanogram represents normal pressure and compliance?

A Type A tympanogram is indicative of normal middle ear pressure and compliance. In a Type A tympanogram, the peak of the graph occurs at atmospheric pressure (0 daPa), showing that the pressure in the middle ear is equal to the external atmospheric pressure. This reflects a functioning eustachian tube allowing for proper equalization of pressure, and the compliance indicates that the tympanic membrane is adequately mobile, suggesting no significant fluid, ossicular discontinuity or other middle ear pathology.

Other types of tympanograms illustrate different conditions. A Type B tympanogram often indicates fluid in the middle ear or a perforation of the tympanic membrane, as it shows a flat curve with no distinct peak. A Type Ad tympanogram reflects hypercompliance indicating ossicular chain discontinuity or other conditions that cause excessive mobility of the tympanic membrane. Conversely, a Type As tympanogram suggests a stiff system, often associated with otosclerosis or other issues resulting in reduced compliance. Each of these alternatives corresponds to specific ear-related conditions, highlighting that Type A is the norm for both pressure and compliance.